Koro Ruapehu is constantly changing. Sometimes he's sleeping, sometimes he's active – sometimes he erupts. Click here for information from GNS on what Koro is doing at the moment. It lets us know how safe it is (or not) to be on the maunga. 

An image from one of the GNS monitoring camera

An image taken from one of the GNS monitoring cameras.

Gas emission at Mt Ruapehu returns to normal 

Volcanic Alert Level remains at 1 Aviation Colour Code remains at Green

Carbon Dioxide (CO2) gas emission rates at Mt Ruapehu have returned to a more normal level. The period of slightly higher volcanic unrest appears to have ended.  On December 5 the Carbon Dioxide (CO2) gas emission rate at Mt Ruapehu was measured as 440 tonnes/day, a substantial reduction from the rate of 2290 tonnes/day measured on November 23. 

An emission rate of 440 tonnes/day is less than the average emission rate over the last 10 years.
Emission rates of Sulphur Dioxide (SO2) and Hydrogen Sulphide (H2S), were also measured on December 5, both well below measurements from November 23. No additional water or gas composition data have been collected from the Crater Lake (Te Wai ā-Moe) since mid-November. Over the last two weeks the volcanic tremor at Mt Ruapehu has been at low or moderate levels, but the strongest since late 2016. 

The lake temperature has risen from 36 oC to 38 oC in the last week, evidence of continued heat entering the lake.
The period of slightly higher volcanic unrest, which was inferred largely from the high CO2 gas emission rate measured on November 23, now appears to have ended.

Posted by 12 December 2017 15:02:00

Slight changes in water and gas composition of the Crater Lake (Te Wai ā-Moe) at Mt Ruapehu 

Measured changes in crater lake water and gas composition confirm the slightly elevated level of activity at Mt Ruapehu. The lake temperature (37ºC) and the level of seismic tremor remain unchanged. The Volcanic Alert Level remains at 1.
The Crater lake (Te Wai ā-Moe) was visited to sample water and gas on 10 and 17 November 2017. The results from the analyses show a slight increase in Chloride, Sulphate and Magnesium concentrations, and CO-CO2 gas ratio. These changes are consistent with the increase in CO2, SO2 and H2S emission rates measured on 23 November and the sustained high lake temperature (~37ºC) reported in our latest bulletin on Saturday 25 November 2017.
The increase in concentration of these chemical elements, higher gas output and a sustained high lake temperature all suggest a more open pathway for the volcanic gases from depth to the surface. These increases are common in periods of higher lake temperature and have been observed in the past outside eruptive periods. Volcanic seismic tremor is currently at moderate to low levels. Further sampling of the Crater Lake and a gas measurement flight are planned as weather allows.
As weather cleared out overnight, a small steam plume was visible this morning above the crater lake at Ruapehu. Such steam plumes are to be expected due to the current combination of higher lake temperature, gas emissions and atmospheric humidity.
GNS Science continues to closely monitor Mt Ruapehu and our other active volcanoes through the GeoNet project. The Volcanic Alert Level of Ruapehu remains at 1 and the Aviation Colour Code at Green.
Agnes Mazot
Duty Volcanologist

Posted by 28 November 2017 18:50:00

High volcanic gas emission and Crater Lake (Te Wai ā-Moe) temperature at Mt Ruapehu 

No change to Volcanic Alert Level
An increase in volcanic gas emissions and sustained high lake temperature suggest a slightly higher level of activity at Mt Ruapehu.
The Volcanic Alert Level remains at 1. The recent fine weather has allowed GeoNet to make airborne gas measurements over Mt Ruapehu. These recorded high levels of CO2, SO2 and H2S emission from the Crater Lake (Te Wai ā-Moe).
The CO2 emission rate on 23rd November was 2290 tonnes/day, one of the largest values recorded in recent years. The current lake temperature is 37° C, which is near the top of its usual range and has been sustained over the past 2 months. The data are consistent with open vent degassing of Ruapehu.
Higher than usual temperatures and high gas fluxes like we have now are common in the open vent situation and have been observed in the past outside eruptive periods.
Volcanic seismic tremor remains at moderate levels. The fine weather has also allowed the taking of water samples from Ruapehu Crater Lake and the analysis of these samples is underway.
GNS Science continues to closely monitor Mt Ruapehu and our other active volcanoes through the GeoNet project. The Volcanic Alert Level of Ruapehu remains at 1 and the Aviation Colour Code at Green.
Tony Hurst Duty Volcanologist

Posted by 25 November 2017 12:16:00

Lake temperature peaks at 43 °C marking end of heating cycle 

Te Wai ā-moe reached a recent temperature high of 43 °C on 5 September marking the peak of the current heating cycle. For much of August the lake temperature rose at about 1 °C per day, starting from a low 23 °C, reaching the peak of 43 °C. Calculations indicate that around 600 MW of heat energy was needed to heat the lake, being about the same as the heat required to generate electricity from one of our geothermal power stations. The lake temperature is now 39 °C.

The post 1995/1996 Crater Lake displays temperatures that typically range between about 16 and 38 °C. In early August, we reported on the variations in the lake temperature. The lake had cooled to a low of 19 °C at that time. GeoNet obtains temperatures from the lake using a data logger with a temperature sensor in the lake and communications via a satellite link. In the August story, we discussed the variations of the lake temperature. An analysis of the lake temperature data since 2009 when we installed a datalogger shows that for 5% of the time it is warmer than 38 °C and another 5% it is cooler than 16 °C. The median temperature is 24 °C. Looking at the longer-term Crater Lake temperature data, collected from lake visits since 1950, the behaviour is similar.

The heating and cooling cycles are controlled by a mix of volcanic and geothermal processes. The results of the lake sampling in mid-August reflected the heating. Further sampling and visits to the Crater Lake are planned as the weather allows, being part of the standard GeoNet monitoring programme for Mt Ruapehu.

http://www.geonet.org.nz/news/7SaU20IDE4G8SU6wsocqY

Posted by 13 September 2017 07:27:00

Seismic activity increases after lake temperature peaks 

From GNS

Alert Status:
Volcanic Alert Level 
remains at 1
Aviation Colour Code
remains Green

Since early September, Mt Ruapehu’s Crater Lake had been heating at a rate of around 1°C per day, reaching a maximum of 40ºC on October 4. The lake temperature has cooled slightly since then and is now hovering around 37°C. After October 18, the level of volcanic tremor under Mt Ruapehu increased in strength. Volcanic tremor is always present at Mt Ruapehu, however the level can vary.

An increase in the strength of volcanic tremor began on October 18, where a sharp increase was noted before the energy declined a day later. Subsequent tremor increases occurred again on October 25 and 28, and currently remains higher than normal. These tremor pulses do not appear to be related to any variation in the lake temperature. Our records show that similar periods of increased volcanic tremor were present May-June 2016, again when the lake temperature was high. Importantly, no eruptive activity or geysering was noted in Crater Lake during the previous periods of volcanic tremor.

Weather conditions have not been ideal for mountain observations. Nevertheless, our scientists will be visiting the lake to collect water samples for further analysis and making a gas flight when the weather conditions improve.

The active crater at Mt Ruapehu is occupied by Crater Lake and it displays temperatures that typically range between about 15 and 40°C and the phases can last between about 9 and 20 months. The lake cooled to a minimum of 12°C in mid-August and then remained at 13-14°C until early September when it started to heat again and reached a peak of 39.8°C on October 4.

GNS Science volcanologists continue to closely monitor Ruapehu through the GeoNet project. The Volcanic Alert Level for Mt Ruapehu remains at Level 1 (minor volcanic unrest) and the Aviation Colour Code also remains unchanged at Green. The Volcanic Alert Levelranges from 0 to 5 and defines the current status at a volcano. Aviation Colour Codes are based on four colours and are intended for reference only in the international civil aviation community.

Brad Scott
Duty Volcanologist

Posted by 31 October 2016 15:09:00

Mt Ruapehu Crater Lake: Steam plumes as lake heats 

This morning, steam plumes have been visible above Mt Ruapehu’s Crater Lake. The lake temperature is now 37 ºC as part of a heating episode that began around 2-3 September 2016. No seismic or acoustic activity has been recorded this morning, indicating the steam plume was not generated by activity in the lake. The Volcanic Alert Level for Mt Ruapehu remains at Level 1 (minor volcanic unrest) and the Aviation Colour Code also remains unchanged at Green.

The active crater at Mt Ruapehu is occupied by Crater Lake. Crater Lake displays temperatures that typically range between about 15 and 40 °C and the phases can last between about 9 and 20 months. The lake cooled to a minimum of 12 °C in mid-August and then remained at 13-14 °C until early September when it started to heat again. Based on past experience, as the lake continues to heat up, more occasional steam plumes can be expected. This is often controlled by atmospheric conditions near the mountain.

There have been no local volcanic earthquakes or changes in the levels of volcanic tremor this morning on the GeoNet instruments at Ruapehu. GNS Science volcanologists continue to closely monitor Ruapehu through the GeoNet project.

 

Posted by 30 September 2016 15:58:00

Ruapehu Crater Lake: Rapid turn around in lake temperature 

From GNS - 7 September

In early August we discussed the possibility of the post 1995/1996 Crater Lake reaching a new low temperature as the lake was cooling strongly at that time. The lake reached a new minimum temperature of 12.0 °C on 15 August. For much of August the lake temperature ranged 13-14 °C, occasionally looking like it maybe going to turn and start heating. The temperature was starting to rise, very slowly, in late-August, but with quite a bit a lot of variability. However by 2 September a rising trend was clearly established. The lake temperature is now 17.6 °C.

On May 11 2016 the lake reached a high of 46°C, the highest we have observed since it reformed in 1999-2000. This high temperature was also accompanied by volcanic tremor and an increase in the output of volcanic gas. The Volcanic Alert Level (VAL) was raised to Level 2 at that time, lowering to Level 1 in early July when the gas output and volcanic tremor levels declined. About 2 days after the lake temperature stared to rise on 2 September, the level of volcanic tremor also started to rise and has remained present since 4 September. The heating and cooling cycles are controlled by a mix of volcano and geothermal processes. Further sampling and visits to the Crater Lake are planned as the weather allows, being part of the standard GeoNet monitoring programme for Mt Ruapehu.

Posted by 12 September 2016 18:21:00

Mt Ruapehu Crater Lake: lake is now cool, volcanic unrest still low 

 Last week a Crater Lake sampling and gas flight were completed by GeoNet staff at Mt Ruapehu. Observations and data from these activities confirm the Crater Lake is still cooling, but at a slower rate and there is volcanic gas passing through the lake. The temperature of the summit Crater Lake is now 13 ºC. The observations from the gas flight and sampling indicate the vent(s) on the lake floor are open, allowing gas, steam and water to vent into the lake. These are typical conditions for Mt Ruapehu. 

The volcanic alert level for Mt Ruapehu remains at Volcanic Alert Level 1 (minor volcanic unrest). The Aviation Colour Code also remains unchanged at Green. 

The gas flight completed on August 10 recorded the volcanic gas at levels typical of low-background output for Mt Ruapehu. Convection was noted in the lake. On August 11 a Crater Lake sampling for gas and water was also completed. Up welling was again obvious in the lake and was outlined by sulphur slicks, which are frequently seen when the lake is convecting. The lake was a dark green-grey colour and was overflowing. There was a fairly strong sulphur smell near the lake. The lake temperature was measured at 12.6 ºC, consistent with the data logger observations. Today the data logger reports a temperature of 12.9 ºC. 

The level of volcanic tremor which was elevated to moderate levels in May-June has declined and is now at typical background levels. Data available at present indicates the level of volcanic unrest at Mt Ruapehu is low. 

GNS Science volcanologists continue to closely monitor Ruapehu through the GeoNet project. 

Steve Sherburn Duty Volcanologist

Posted by 16 August 2016 06:09:00

Volcanic Advisory removed for Ruapehu’s summit craters area 

The Department of Conservation has removed the area of caution around the summit area of Mt Ruapehu due to a reduction in Volcanic Alert Level to normal. The Department has removed the advice not to enter the crater basin area, camp anywhere in the summit craters or travel in the floors of the upper parts of valleys draining the crater basin. This removes the area of caution advised by DOC in May. As before, normal operations continue for visitors to all areas outside the summit craters and upper valleys.

GNS Science issued a Volcanic Alert Bulletin on 11 May raising the Volcanic Alert Level from 1 to 2 (elevated volcanic unrest) due to heating of the Crater Lake and other associated indicators of increased volcanic unrest. They continued to monitor the volcano closely and on 17 May issued a second Bulletin noting early signs the heating might have peaked.

On 5 July GNS Science issued a further bulletin lowering the Volcanic Alert Level for Mt Ruapehu to 1 (minor volcanic unrest) noting the decrease in gas emission and volcanic tremor to normal levels. VAL 1 is the normal level for the mountain. People away from the volcano were never affected by the now-cancelled advisory, and visitors were not being warned to stay away from the mountain. “The public at all three ski areas, roads and areas surrounding the mountain were not, and are not, affected” says Paul Carr, Tongariro National Park Operations Manager for Public Safety.

“Full winter conditions now exist on the mountain. People going above the park’s road ends should be fully equipped with alpine clothing, crampons and ice axe, know how to use them and take account of the weather forecast” he said.The level of unrest at Mt Ruapehu is continually monitored by GNS Science through the GeoNet project. The aim is to ensure any changes in the volcanic state are detected at the earliest possible time and communicated to DOC and RAL so appropriate procedures can be put in place.

Posted by 06 July 2016 07:29:00

Volcanic Alert Level lowered to Level 1 for Mt Ruapehu 

GNS reports that the moderate to high level of volcanic unrest at Mt Ruapehu is no longer present and the Volcanic Alert Level is now lowered to Volcanic Alert Level 1, minor volcanic unrest. 

The gas emissions decreased and the level of volcanic tremor has also declined. The temperature of the summit Crater Lake has declined from 46 ºC (11 May) and is now at 23ºC.

The Aviation Colour Code is also changed, going from Yellow to Green. 

A gas flight was completed yesterday and recorded the gas output at levels typical of background for Mt Ruapehu. The level of volcanic tremor which has been elevated to moderate levels has declined and shows now similar levels to what it was in the second
half of 2015. The lake temperature measured by the outlet data logger is now 23 ºC. 

After reaching a high of 46 ºC on May 11 the lake started to cool to the current value of 23 ºC. Data available at present indicates the period of elevated volcanic unrest at Mt Ruapehu is over. 

The volcanic alert level for Mt Ruapehu is now lowered Volcanic Alert Level 1 (minor volcanic unrest). The Aviation Colour Code is also changed from Yellow to Green.

GNS Science volcanologists continue to closely monitor Ruapehu through the GeoNet project.

 

Agnes Mazot
Duty Volcanologist

Posted by 05 July 2016 13:51:00
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